JP2006148096A - Adhesive tape for fixing semiconductor wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive tape for dicing that prevents cut junk from remaining on a semiconductor wafer's surface in full-cutting dicing. <P>SOLUTION: This is an adhesive tape for fixing a semiconductor wafer that melts at a testing temperature of 190 °C and test load of 21.18 N in the testing method shown in "the flow testing method of thermoplastics" Japanese Industrial Standards K 7210, wherein MFR by the method is 0.1-3, and a resin layer B and adhesive layer A are laminated that includes a carboxyl group as a polymeric constituent. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an adhesive tape used in a process for producing various semiconductors. More specifically, for example, the present invention relates to an adhesive tape for fixing a semiconductor wafer that is used to fix the semiconductor wafer when the semiconductor wafer on which the pattern is formed is cut into individual patterns and divided into elements. .

For the dicing process that cuts and separates the semiconductor wafer on which the circuit pattern is formed into small pieces, the semi-full cut method that cuts only the semiconductor wafer with a rotating round blade and bonding to the back of the wafer to fix the semiconductor wafer There is a full cut method in which a part of the wafer fixing tape is cut. Dicing conditions for semiconductor wafer dicing are set appropriately depending on the type of wafer. For example, a 4 MB-DRAM wafer having a diameter of 6 inches and a thickness of 200 μm has a peripheral speed of a rotating round blade of about 100 m / sec and a cutting speed. Full-cut dicing is performed at 100 mm / second, a cutting depth of 30 μm into the adhesive tape for fixing a semiconductor wafer, and a supply amount of cutting water (cooling water) of 20 cc / second. Wafer-fixing adhesive tapes are required to have two performances: element-piece fixing force when cutting a semiconductor wafer and easy peelability when each element piece is mounted one by one. In recent years, radiation curable pressure-sensitive adhesive tapes as disclosed in JP-A-01-249877 have been used. The full cut dicing method has been widely used in conjunction with the advent of radiation curable pressure-sensitive adhesive tapes for the purpose of saving labor in the semiconductor manufacturing process and improving semiconductor quality. However, as the degree of integration of semiconductor wafers increases, the level of requirement for residue management on the wafer surface becomes stricter, and residues on the wafer surface of cutting waste generated during full-cut dicing are becoming a problem to be addressed. Conventionally, since the cutting scrap generated by the semi-full cut method is only the powder of the wafer, it is easily removed by cleaning water and does not cause a semiconductor wafer defect. However, as cutting waste generated by the full-cut dicing method, in addition to wafer waste, thread-like waste that is melted and stretched at the time of cutting of the wafer fixing adhesive tape is generated, and this cutting waste is caught by unevenness on the wafer surface and remains. There is a problem. In order to solve such a problem, the technique disclosed in Patent Document 1 or 2 has been proposed, but the strict demand for residue management for the semiconductor wafer as described above has not been sufficiently met. Absent.
JP-A-5-156214 Japanese Patent Laid-Open No. 5-21234

  An object of this invention is to provide the adhesive tape for semiconductor wafer fixation which solved said problem. That is, the present invention provides a pressure-sensitive adhesive tape for fixing a wafer capable of preventing cutting chips from remaining on the surface of a semiconductor wafer even in the full-cut dicing method.

As a result of repeated studies to achieve the above object, the present inventors have <1> the cutting waste generated during dicing of the semiconductor wafer into a long and slender thread shape, and thus easily caught by the irregularities on the surface of the semiconductor wafer, <2> Furthermore, the heat generated when the rotating round blade cuts the semiconductor wafer causes the constituent resin of the wafer fixing tape to be cut together with the wafer to be in a molten state, and is drawn into a thread by the rotation of the rotating round blade. I found it. As a result of further diligent research, the use of a specific polymer for the resin layer of the base of the wafer fixing tape does not cause the cutting waste generated during dicing of the semiconductor wafer to be in the form of a thread, effectively remaining on the wafer surface. Based on this finding, the present invention has been completed.
That is, the present invention
(1) Melting at a test temperature of 190 ° C. and a test load of 21.18 N in the test method shown in JIS K 7210 “Thermoplastic flow test method” and having an MFR of 0.1 to 3 by the above method, and a polymer A pressure-sensitive adhesive tape for fixing a semiconductor wafer, comprising a resin layer B containing a component having a carboxyl group (—COOH) as a component and an adhesive layer A,
(2) The semiconductor wafer according to (1), wherein the resin layer B containing a component having a carboxyl group is an ethylene- (meth) acrylic acid copolymer or an ethylene- (meth) acrylic acid copolymer ionomer resin. Fixing adhesive tape,
(3) There is a resin layer B-1 having a thickness of 20 μm or less between the resin layer B and the pressure-sensitive adhesive layer A and a melting point by DSC measurement of 100 ° C. or higher, and the thickness of the pressure-sensitive adhesive layer A and the resin layer B-1 (1) The adhesive tape for fixing a semiconductor wafer according to (1) or (2), and (4) the resin layer B in the adhesive tape for fixing a semiconductor wafer has a round round blade of 10 μm or more. A semiconductor wafer full-cut dicing method using the adhesive tape for fixing a semiconductor wafer according to any one of (1) to (3), which is characterized by being cut.

  The adhesive tape for fixing a semiconductor wafer of the present invention is particularly suitable for use in a full-cut dicing method, and in the full-cut dicing method, no cutting waste remains on the surface of the semiconductor wafer, improving the production yield of the semiconductor wafer, It has an excellent effect of greatly contributing to the improvement of reliability.

  The present invention is described in detail below. During semiconductor wafer dicing, cutting water is supplied to cutting points on the wafer surface in order to cool the heat generated when the rotating round blade cuts the wafer and clean the wafer surface. With heat, it rises to near 100 ° C., the boiling point of cutting water. In addition, when the cutting depth of the rotary round blade to the wafer fixing adhesive tape is deep, the supply of cutting water becomes insufficient, and a sufficient cooling effect can be expected only up to about 20 μm of the surface of the tape thickness. In the depth portion, the temperature of the workpiece may rise to 100 ° C. or more due to insufficient supply of cutting water. For this reason, in the conventional adhesive tape for wafer fixing, the resin of the base film is melted and stretched at the time of cutting, and thread-like cutting waste is generated. The adhesive tape for wafer fixing of the present invention prevents the generation of thread-like cutting waste at such a high temperature state. One embodiment of the adhesive tape for fixing a wafer of the present invention is shown in FIG. The figure is a longitudinal sectional view of an adhesive tape, in which one adhesive layer A and two resin layers B are laminated. The resin layer B is characterized by being a resin having an MFR of 0.1 to 3 and containing a carboxyl group as a polymer constituent component. Even when the resin of the resin layer B is melted by cutting heat during wafer dicing, the resin layer has a very high melt viscosity because the MFR of the resin is 0.1 to 3, and Since it contains a carboxyl group, it has good affinity with cutting water. As a result, it is considered that the cutting waste is easily cut finely when stretched by the rotating round blade and is not stretched long and thin, so that generation of thread-like cutting waste can be prevented. Here, the content of the carboxyl group is 5 parts by weight or more as a component having a carboxyl group as a polymer component (for example, MAA: methacrylic acid comonomer) with respect to 100 parts by mass of the main constituent resin of the resin layer B, more preferably 8 to 20 parts by weight is appropriate. Moreover, said MFR of resin used for the resin layer B is 0.1-3.

  In order to prevent the generation of thread-like cutting waste, it is preferable to increase the cutting depth of the rotating round blade into the resin layer B having the effect of suppressing the thread formation of the cutting waste. Since the tape cutting depth is often set to around 30 μm, the adhesive layer A positioned between the wafer and the resin layer B is preferably as thin as possible, for example, 3 to 20 μm is preferable, and more preferably 5 to 15 μm. It is.

Since the resin of the resin layer B is selected on the assumption that it becomes a molten state by cutting heat, the viscosity when the resin is in a molten state is more important than the melting point of the resin. As such a resin, a resin containing a compound having a MFR of 0.1 to 3 and a carboxyl group as a polymer constituent unit is used. An ethylene- (meth) acrylic acid copolymer of MFR 0.1 to 3, ethylene- An ionomer resin of a (meth) acrylic acid copolymer is used.
In the ionomer resin, as the cation for neutralizing the carboxyl group, a metal ion or an organic amine is usually used, and among them, metal ions such as Na ⁺ , Li ⁺ , Mg ⁺⁺ , Zn ⁺⁺ are mainly used. It is done. In order to prevent an adverse effect on the semiconductor wafer, an ionomer using Zn ⁺⁺ as a cation is preferably used. The neutralization degree of the carboxyl group with a cation is preferably 5 to 90 mol%. The thickness of the resin layer B is not particularly different from the base resin layer of a normal adhesive tape for fixing a semiconductor wafer. Usually, it is 30-300 micrometers, More preferably, it is 50-200 micrometers.

  Furthermore, another embodiment for further preventing the generation of thread-like cutting waste is shown in FIG. 2 as a cross-sectional view. In the drawing, three resin layers B-1 having a melting point of 100 ° C. or higher are used at positions where the cutting temperature is suppressed to 100 ° C. or lower by supplying cutting water. The reason for this is that the cutting temperature of the resin layer B-1 is suppressed below the melting temperature of the resin layer B-1 due to the cooling effect of the cutting water, so that melting and stretching during cutting can be avoided, and the resin layer B-1 This is because it is difficult to become thread-like cutting waste. In addition, the resin layer B that is cut at the same time is mixed with the resin of the resin layer B-1 that has been cut away by cutting and is not melted, and thus the effect of preventing the resin layer B from becoming filamentous is enhanced. As the position of the resin layer B-1 at which the cutting temperature can be suppressed to 100 ° C. or less, a thickness of about 20 μm from the adhesive tape surface is preferable in consideration of the cooling effect of the cutting water. In this case, the adhesive of the adhesive tape It is preferable to suppress the sum of the thicknesses of the layer A and the resin layer B-1 having a melting point of 100 ° C. or higher to 20 μm or less.

As resin of resin layer B-1, melting | fusing point of resin is important in order to avoid the fusion | melting by cutting heat, and it is preferable that it is 100 degreeC or more of melting | fusing point from the relationship with the boiling point of cutting water. The melt viscosity is not particularly limited because the resin is used at a temperature below the melting point, and an appropriate resin is selected for ease of film formation. Is preferably used. Moreover, since resin layer B-1 is located between the resin layer B and the adhesive layer A, both adhesiveness is also required. In order to obtain adhesiveness with the resin layer B, it is preferable that the resin of the resin layer B-1 is similar to or similar to the resin of the resin layer B. In order to obtain adhesiveness with the pressure-sensitive adhesive layer A, the resin of the resin layer B-1 has a polar group or a resin that can easily have a polar group by modifying the film surface such as corona treatment. It is preferable. As such a resin, for example, ethylene-methacrylic acid copolymer (EMAA)
Ethylene-methyl methacrylate copolymer (EMMA)
Ethylene-vinyl acetate copolymer (EVA)
Ethylene-ethyl acrylate copolymer (EEA)
Ethylene-acrylic acid copolymer (EAA)
Ethylene-methyl acrylate copolymer (EMA)
For example, a resin having a melting point of 100 ° C. or higher can be given.

  In addition, the resin layer B and the resin layer B-1 are not limited to one layer each, and the resin layer B and the resin layer B-1 need only satisfy the required conditions. Yet another embodiment is shown in cross-sectional view in FIG. The figure shows an example in which another resin layer B-2 indicated by 4 is laminated on the surface of the resin layer B opposite to the side laminated with the resin layer B-1 or the pressure-sensitive adhesive layer A. However, the resin layer B-2 is not limited to one layer, but it is necessary to satisfy the conditions required for the resin layer B when the resin layer B-2 is cut from a rotating round blade during dicing. In this embodiment, when the surface of the resin layer B-2 or the resin layer B-2 laminated on the resin layer B on the side opposite to the side where the adhesive layer A is applied is subjected to texture processing or lubricant coating, blocking prevention, adhesive tape This is preferable because there is an effect such as prevention of necking of the base film by reducing friction between the adhesive tape and the jig during radial stretching. 1 to 3 indicate the same components.

  Next, the pressure-sensitive adhesive used for the pressure-sensitive adhesive layer A in the present invention is not particularly limited, but an acrylic pressure-sensitive adhesive is preferably used. Moreover, in order to impart radiation reactivity, additives such as monomers, oligomers, polymers and photoinitiators having a carbon-carbon double bond in an acrylic pressure-sensitive adhesive may be formulated and used as necessary. it can. Known adhesives can be used, and for example, those described in JP-A-1-249877, Japanese Patent Application No. 5-196768, JP-A-63-17980, and the like can be used. The semiconductor wafer dicing method itself using the adhesive tape for fixing a semiconductor wafer of the present invention can be performed in the same manner as a normal method except for the points described above. However, these adhesive tapes for fixing a wafer are used. In order to prevent thread-like cutting waste during dicing, it is preferable that the rotating round blade cut the amount of cutting of the rotating round blade at the time of semiconductor dicing into the resin layer B of the wafer fixing adhesive tape by 10 μm or more.

Next, the present invention will be described in more detail based on examples. In the following examples, each characteristic was tested and evaluated as follows.
<1> Melting point The value measured under the test conditions of a heating rate of 10 ° C. per minute in a nitrogen gas atmosphere by DSC (finger scanning calorimetry) shown in JIS K 7121 “Plastic transition temperature measurement method” It was.
<2> MFR
The measurement was performed under the test conditions of a test temperature of 190 ° C. and a test load of 21.18 N {2.160 kgf} as shown in JIS K 7210 “Method for testing the flow of thermoplastics”.
<3> Cutting chip residue test The surface of 100 to 10,000 element pieces of a semiconductor wafer diced under the following conditions was observed with an optical microscope for the presence of cutting chips at a measurement magnification of 100 times. We investigated the incidence of chips that have generated. A value of 0.3% or less was regarded as acceptable (◯), and a value exceeding 0.3% was regarded as unacceptable (x).
(Dicing conditions)
Dicing machine: DTF-2 / 6 type rotating round blade made by DISCO: 2060-27HFDD made by DISCO
Rotating round blade Rotation speed: 30,000rpm
Cutting speed: 100 mm / s
Cutting water flow rate: 20 ml / s
Dicing size: 2mm square

Example 1
As the resin layer B, an EMAA resin ^{* 1} (Mitsui / DuPont Polychemical Co., Ltd., Nucrel N0903HC) having an MFR of 3.0 and a melting point of 98 ° C. was used to prepare a resin layer B having a thickness of 100 μm. Further, after corona treatment was applied to the surface of the resin layer B to improve the adhesiveness of the adhesive, an acrylic adhesive was applied to the surface of the resin layer B so as to have a thickness of 10 μm after drying, as shown in FIG. A similar adhesive tape was prepared. In the dicing process, the cutting depth of the rotary round blade into the tape was set to 30 μm, and the evaluation was performed. The results are shown in Table 1.

Comparative Example 1
As the resin layer B, an adhesive tape was prepared and diced in the same manner as in Example 1 except that EVA resin ^{* 2} (manufactured by Tosoh Corporation, Ultrasen UE-630) having an MFR of 1.5 and a melting point of 90 ° C. was used. Evaluation was performed. The results are shown in Table 1.

Comparative Example 2
An adhesive tape was prepared, diced, and evaluated in the same manner as in Example 1 except that MFR10 and EMAA resin ^{* 1} (Mitsui / DuPont Polychemical Co., Ltd., Nucrel N410) having a melting point of 97 ° C. was used as the resin layer B. Went. The results are shown in Table 1.

(Note) EMAA resin ^{* 1} : Ethylene-methacrylic acid copolymer EVA resin ^{* 2} : Ethylene-vinyl acetate copolymer

It is a longitudinal cross-sectional view which shows one embodiment of the adhesive tape for semiconductor wafer fixation of this invention. It is a longitudinal cross-sectional view which shows the other embodiment of the adhesive tape for semiconductor wafer fixation of this invention. It is a longitudinal cross-sectional view which shows other embodiment of the adhesive tape for semiconductor wafer fixation of this invention.

Explanation of symbols

1 Adhesive layer A
2 Resin layer B
3 Resin layer B-1
4 resin layer B-2

Claims (4)

  Constituents of the polymer that melt at a test temperature of 190 ° C. and a test load of 21.18 N in the test method shown in JIS K 7210 “Thermoplastic flow test method” and have an MFR of 0.1 to 3 by the above method A resin wafer B containing a component having a carboxyl group (—COOH) and a pressure-sensitive adhesive layer A are laminated, and a pressure-sensitive adhesive tape for fixing a semiconductor wafer.   The pressure-sensitive adhesive for fixing a semiconductor wafer according to claim 1, wherein the resin layer B containing a component having a carboxyl group is an ionomer resin of an ethylene- (meth) acrylic acid copolymer or an ethylene- (meth) acrylic acid copolymer. tape.   There is a resin layer B-1 having a thickness of 20 μm or less between the resin layer B and the pressure-sensitive adhesive layer A and having a melting point of 100 ° C. or higher as measured by DSC, and the sum of the thicknesses of the pressure-sensitive adhesive layer A and the resin layer B-1 The adhesive tape for fixing a semiconductor wafer according to claim 1 or 2, wherein the adhesive tape is 20 µm or less. A full semiconductor wafer using the adhesive tape for fixing a semiconductor wafer according to any one of claims 1 to 3, wherein a rotary round blade is cut into the resin layer B of the adhesive tape for fixing a semiconductor wafer by 10 µm or more. Cut dicing method.

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